Skip to content


Just a couple lines to tell you how proud I am to have been appointed an expert of "Los 100 de COTEC". COTEC Foundation has the mission to promote innovation as an engine of social and economic development. In the last few years, it has become a true agent of change that contributes to the development of the Spanish economy and society, based on a more ambitious definition of the concept of innovation: "Innovation is any change (not only technological) based on knowledge (not only scientific) that generates value (not only economic)."

Los 100 de COTEC is a network of experts who speak Spanish, from multiple areas of knowledge, prepared to analyze the great social, economic and technological challenges facing innovation. They stand out for their training, experience, relational capital and capacity for dissemination.

I'm really honored to join such a distinguished network and I hope I can help COTEC pursue their goals.

I have a new paper out with Ignacio Tamarit and José A. Cuesta on the structure of personal relationships. In short: we extend the idea of Dunbar circles to the continuum so all types of data can be considered. In more detail: In the early 2000's Robin Dunbar and co-authors showed that our personal relationships are organized in circles: 3-5 very close relationships, add 10-12 for the circle of close friends, another 30-40 join as friends, and acquaintainces add up to about 150. Note that the size of circles scale by a factor of 3: the sequence is approximately 5-15-50-150. Beyond that, there is evidence for a larger circle of ~500 people, see e.g., the paper by Miranda Lubbers, José Luis Molina and Hugo Valenzuela. There is a lot of empirical evidence that the circles exist. But in 2018, our team along with Robin Dunbar showed mathematically that this is the only way relationships of different intensities can be organized if cognitive capacity is limited. In fact, our theory predicted the circles as we know it, but also another regime that should be observed in small populations, where almost everybody is in the first circle for lack of enough people to be friends with (inverted regime). Data from José Luis Molina confirmed it.

However, the division on circles is somewhat arbitrary, and often data on relationships is continuous, like duration of phone calls or of face-to-face encounters. In our new paper we develop the corresponding mathematical theory to describe this. We check our theory with data from phones (Sune Lehmann et al), from face-to-face encounters (Ciro Cattuto, Alain Barrat et al) and from facebook (Arnaboldi et al). The theory describes pretty well all these datasets, and a majority of the individuals in the data are well described by one-parameter theory, with parameter value 6, which is in exact correspondance with the 3 factor of the discrete Dunbar circles. Thus, the model captures a universal feature of how we manage our relationships, and makes it clear that their structure exhibits the signature of a resource allocation problem both in the discrete and in the continuum versions. Stay tuned for further, awesome evidence of this limited resource mechanism in other contexts, hopefully coming out soon in a journal near you. Thanks to Ignacio and Jose, and to Robin Dunbar for support.

El proyecto IBSEN, del que soy responsable, va a comenzar la campaña 21-22 de experimentos, así que como miembro de nuestra comunidad universitaria, te invitamos a colaborar con nuestra investigación participando en los experimentos del proyecto (, breve video resumen en IBSEN es un proyecto de investigación que fue financiado por el programa Horizonte 2020 de la Unión Europea y que en la actualidad sigue adelante desarrollado por investigadores del Grupo Interdisciplinar de Sistemas Complejos (GISC, 

A finales de octubre o principios de noviembre comenzaremos a lanzar experimentos, y para ello te pedimos tu colaboración.

Si ya conocías el proyecto y estás inscrito en nuestra base de datos de voluntarios, no tienes que hacer nada.

Si no nos conocías y te inscribes como se indica debajo, en cuanto retomemos las sesiones experimentales, en un plazo de unas semanas, recibirás información por correo electrónico sobre la posibilidad de participar. 
Una vez abierta una sesión o sesiones de un experimento, solo tienes que inscribirte en la que quieras hasta completar los voluntarios necesarios (normalmente en cada experimento solo se podrá participar una vez). La participación en estos experimentos, que están sujetos a aprobación del Comité de Ética de la Universidad, involucra sólo decisiones sencillas en situaciones modelo, y todos los datos que se generan se anonimizan, con lo que tu privacidad está perfectamente salvaguardada. Además, en la mayoría de experimentos, recibirás una pequeña remuneración económica por tu participación. La participación es online en la gran mayoría de los casos, por lo que no necesitarás desplazarte a ningún sitio para ser voluntario.

Muchos experimentos se anuncian primero en Twitter para no bombardearte con correos electrónicos, y muchas veces se llenan sin necesidad de llegar a enviar correos. Si quieres recibir información por esta vía, sigue a @IBSEN_H2020.

Para inscribirte y poder participar en nuestros experimentos, haz click en para registrarte e incorporar tus datos de contacto y algunos datos demográficos a la base de datos IBSEN. 

Beneficios por tu participación:       

1) Contribuirás a la ciencia y a la mejora global de la sociedad.       
2) Proporcionarás visibilidad internacional a la investigación de la UC3M.              
3) Recibirás una pequeña remuneración económica inmediata cuando participes en alguno de nuestros experimentos.

Finalmente, te agradeceríamos que difundieras esta información entre todos tus familiares, amigos y conocidos. ¡De esta manera ya nos estarías ayudando! La inscripción está abierta a todo el mundo aunque no sea miembro de nuestra comunidad universitaria. En el espíritu de la ciencia ciudadana y abierta, todos podemos contribuir. 

Para cualquier consulta relativa al proyecto IBSEN, por favor envía un correo a

Algunos ejemplos de trabajos científicos recientes realizados en el marco del proyecto: 

El proyecto IBSEN agradece la colaboración de la Dirección y los Decanatos de los centros de la UC3M para la difusión de esta convocatoria, que será clave para alcanzar nuestros objetivos de investigación, y por supuesto la de todos aquellos que os inscribáis para participar.  

I am very happy to tell you about a new paper of mine coming out in Nature Communications: "Evidence from a long-term experiment that collective risks change social norms and promote cooperation" (open access link) with Aron Szekely, Francesca Lipari, Alberto Antonioni, Mario Paolucci, Luca Tummolini and Giulia Andrighetto.

In the paper, we present results of a long-term, online experiment with ~300 participants specifically designed to unveil the interplay of social norms and facing collective risks (such as, e.g., climate change). First, we show that there is a strong association between contribution and social expectations (empirical and normative expectations), personal beliefs (personal normative beliefs), and dispositions based on unconditional contributions and expectations. Participants increase their contribution in response to higher empirical and normative expectations even reacting to a belief that has no material implication for them. Strikingly, subjects respond more to normative expectations than they do to empirical expectations!

To understand why cooperation changes according to expectations, we use k-means clustering to classify subjects in empirical cooperators, normative cooperators, social norm followers, threshold-driven subjects and unconditional ones. We find stronger social norms in high-risk settings. Risk changes norms and coordinates and motivates social expectations and contributions leading to higher cooperation under high risk, whereas stronger norms provide greater resistance to behavioral change than loose ones.

In summary, we find greater cooperation and stronger social norms in high-risk environments and slower behavior change when risk changes and social norms are stronger. Also, social norms predict cooperation, causally affect behavior, and lead to punishment of norm-breakers. As a general remark, we show that a precise, measurable definition of social norm allows quantitative analyses lead to insights about the feedbacks between norms and behavior, leading to specific predictions of optimal behavioral change interventions relevant to global societal challenges.

A few days ago, the nice people of Talento para el Futuro invited me to give them a talk about behavioral science, experiments, and applications to climate change mitigation. I was happy to oblige and the result was the lecture below (in Spanish)

I'm happy to report that I have a new paper out with Pablo Lozano and Sergey Gavrilets in which we present a model for the emergence of hierarchies compatible with cooperation. A few years ago, in an experimental paper we found that hierarchy (understood as privileged access to jointly generated resources) hinders cooperation among human subjects (although when hierarchy was not linear but in groups this did not occur, see subsequent paper). With the model we have just introduced, we show that when hierarchies are dynamical and can evolve through fights among the individuals, much like in primate societies in general, then a large fraction of people still cooperate. Note that this is not good news, in the sense that what happens typically is that the society splits in an upper class and a lower class, with the former exploiting the latter that has to cooperate in order to have a chance to earn a living. Ugly, but kind of realistic. We believe that this model is a relevant step to understand how egalitarian societies could evolve to hierarchical, class-split ones, highlighting the importance of dynamical hierarchies and suggesting fighting as a possible mechanism for that dynamics.

I have a new paper out with Federico Pablo-Martí and Ángel Alañón-Pardo, in which we use a huge review of historical sources, complex network science and agent-based simulations to show that the road network in Spain is not an invention of the Bourbon kings upon arrival at the throne after the Succession War. The paper is here and I tweeted executive summaries in English and in Spanish (pdf versions can be found respectively here and here).

Along with a bunch of very nice guys, experts in different aspects of climate modeling, machine learning and such, we have published a paper making the case for including social foundations in integrated assessment models. The paper, freely available here, argues that developing effective climate policy means to introduce a coherent methodological perspective by extending IAMs' structure toward economics that takes into account social aspects, such as behavioral, welfare, or political economics. Considering these domains as a bridge between social foundations and IAMs is required for moving from intentions to actions in order to trigger public support for stringent mitigation and to spearhead a profound transformation in climate policies. Once these social foundations are built up in IAMs, they will open up new perspectives for climate actors in terms of mitigation pathways: Indeed, one key outcome of considering social aspects in IAMs—and therefore in climate policies—may be a greater attention to social dynamics for coping with climate change.

I have a new paper out with Luisa De Amicis, Silvia Binenti, Felipe Maciel Cardoso, Carlos Gracia-Lázaro and Yamir Moreno: "Understanding drivers when investing for impact: an experimental study", which appeared today in Palgrave Communications.

Impacting investing aims to generate specific beneficial social or environmental effects in addition to financial gains. Impact investments may take the form of numerous asset classes and may result in many specific outcomes. The point of impact investing is to use money and investment capital for positive social results. In this context, what we did is try and understand the socio-demographic characteristics of investors who choose impact investment options over traditional investments; moreover, we also look into the drivers promoting such choices. To that end, we ran an experiment-based involving 602 participants (non-experts and experts in the financial sector) taking part in a multiple-choice game involving different investment scenarios and incentive conditions.
Our results show that both expert investors and female participants are more likely to choose impact investming, and that the tendency to invest in social funds increases with age. Rather disappointingly, we found no effects of external and centrally planned incentives, such as fiscal incentives, but the educational level of participants did show a significant influence on investing choices. On the other hand, information about the actual social impact achieved by funds does play a role in promoting socially oriented decisions, more strongly if visual aids are displayed prominently when promoting impact investment.

We are confident that our results will attract the interest of policymakers, social campaigners and investing practitioners themselves, in order to devise strategies for raising interest in impact investing or norms to improve the environment for social entrepreneurship more broadly.

Junto con José Luis Molina y Beatriz Patraca, de la Universitat Autònoma de Barcelona, acabamos de empezar una campaña de recogida de datos sobre relaciones sociales/personales en estos momentos de confinamiento en los que nos encontramos. Si quieres colaborar con esta investigación, puedes hacerlo rellenando esta encuesta:

Rellenarla te llevará unos 20 minutos, sobre todo por la parte en que te preguntamos, de manera totalmente anónima, por tus relaciones. Contribuyendo con hasta 25 de ellas nos ayudarás muchísimo en nuestro trabajo, que puede ser importante para entender cómo nos relacionamos estos días y tener relevancia para planificar estrategias futuras de desconfinamiento y prevención.

Una vez la hayas rellenado, puedes conocer más sobre lo que hacemos en este vídeo de 5 minutos que realicé dentro del programa BBVA-El País "Aprendemos juntos".